Almost every day of the year a special ship arrives at Bergen on the southwestern coast of Norway. It has just completed an 11-day round-trip to Kirkenes at Norway's northeastern edge – a hop, skip and a jump from the Russian border. Later that day another ship will leave Bergen on the same journey. These are Hurtigruten (“The Express Route”) ships taking locals and tourists, cars and cargo up and down the west and north coasts of Norway. (Here is a map of the Hurtigruten route.)

A problem, a solution
At the end of the nineteenth century the northern part of Norway was quite isolated from the rest of the country. It's a mountainous country whose jagged coastline is deeply indented by fjords, and punctuated by dangerous reefs, small islands and narrow inlets. The coastline wasn't even properly mapped. But northern Norway had rich fishing grounds and there was a need for a fast and safe trade route between north and south.

Richard With and Anders Holthe took on the job of mapping the coastline, and in 1893 With began the first Hurtigrute service. It visited 11 harbors between Trondheim and Hammerfest. Weather permitting, today's ships call at three times this many harbors. They continue to be a part of the communities they visit and an important means of transportation.

A journey (plus activities)
The coastal ships have carried tourists from the early days, but this element has grown over the decades. Since government subsidies were phased out, it's important in maintaining the service. Tourists are treated to views of exceptional beauty, are able to see a part of the life of another country (unlike the isolation of a cruise ship), can visit historic towns and may opt for activities such as dog sledding, a Viking feast or a visit to Nordkapp (North Cape) at the northernmost point of mainland Europe. In addition to all this there are a few specialist tours, including astronomy.

A seasonal pleasure
But what would be special about astronomy in Norway?

There's certainly nothing special in the summertime when almost the entire 5200-kilometer (3200-mile) round-trip occurs in daylight or twilight. During the northern hemisphere summer, the Earth's north pole is tilted towards the Sun. The ship crosses the Arctic Circle on the fourth day and the Sun doesn't set anywhere above this latitude at the June solstice. Here's a diagram that explains why there is no sunset.

Although the “midnight Sun” is a popular tourist draw, it's no good to astronomers. You don't see stars from the end of April to early August, except for our own star, the Sun. And yet the Sun is the cause of what does draw people to northern Norway during the winter: the aurora borealis, the northern lights.

The northern lights
Aurorae are created by charged particles from the Sun conveyed along Earth's magnetic field lines into the upper atmosphere. These particles excite atoms of oxygen and nitrogen in the air, causing them to give out light of a particular frequency and therefore of a particular color. The main colors are green and red. (See the link to “Aurorae – Polar Light Shows” at the end of this article to learn more.)

The most reliable auroral activity in the northern hemisphere occurs under the auoral oval, an oval-shaped band centered on the magnetic north pole. (There is another one in the southern hemisphere.) So if you go north – though not as far as the north geographic pole – it increases your chances of seeing aurorae. Alaska, Iceland, Greenland and northern Scandinavia are all popular choices.

And astronomy too
In 2008 Dr. John Mason, Principal Lecturer of the South Downs Planetarium and Science Centre in southern England, led a dedicated astronomy tour on a Hurtigruten ship. A few years later, in order to meet the demand, Ian Ridpath began to lead tours as well.

Both of the on-board astronomers are fellows of the UK's Royal Astronomical Society, and are well known as lecturers, broadcasters and writers. Each of them offers a set of lectures to the astronomy group. These include an introduction to aurorae, with other talks dealing with varied aspects of astronomy. For example, John Mason has spoken on “Our Violent Sun” and how the Hubble Space Telescope has revolutionized our understanding of the cosmos. Ian Ridpath tells stories of the constellations and exploring the Moon, amongst others.

Aurorae are unpredictable, so a lot of time can be spent on deck. This means that you can get a tour of the night sky in the darkness of the fjords - it's dark enough to see the Milky Way unless the Moon is too bright. Not only are the dark skies a treat for city dwellers, but beginners who would like to learn to identify constellations have an expert on hand.

In addition, an experienced Norwegian tour guide provides local knowledge and assistance. And since the Northern Lights Planetarium in Tromsř reopened after its renovation, a planetarium visit is part of the program. Unfortunately, northern lights cannot be guaranteed, though there is an excellent chance of seeing a display.

There is a link below to the second part of this article, “Hurtigruten – Seeing the Northern Lights,” the story of what one astronomy tour group saw on their voyage.